U.S. patent number 5,223,112 [Application Number 07/693,844] was granted by the patent office on 1993-06-29 for removable shutter apparatus for a semiconductor process chamber.
This patent grant is currently assigned to Applied Materials, Inc.. Invention is credited to Avi Tepman.
United States Patent |
5,223,112 |
Tepman |
June 29, 1993 |
Removable shutter apparatus for a semiconductor process chamber
Abstract
Removable shutter apparatus for a deposition or etching
apparatus including a shuttering mechanism disposed within a
processing chamber and adapted to carry a shutter plate between a
retracted position and an extended position wherein it is engaged
by a lifting assembly and moved into position closing the normal
plating aperture as if it were a substrate to be processed. When a
new product substrate is presented for processing, the lifting
assembly will lower the shutter plate back onto the shuttering
mechanism and it will be moved to its retracted position out of the
way of the normal handling and processing operation. Because the
shutter plate is geometrically similar to the product substrate and
is handled by the same lift assembly, the same robotic shuttling
mechanism used to transport product substrates into and out of the
chamber may be used to periodically remove and replace a used
shutter plate with a new plate without shutting down the system. An
important advantage of the present invention is that the shutter
closes, and thus "shadows", exactly the same processing aperture
closed by the substrate during its processing.
Inventors: |
Tepman; Avi (Cupertino,
CA) |
Assignee: |
Applied Materials, Inc. (Santa
Clara, CA)
|
Family
ID: |
24786344 |
Appl.
No.: |
07/693,844 |
Filed: |
April 30, 1991 |
Current U.S.
Class: |
204/298.11;
204/298.25; 204/298.15 |
Current CPC
Class: |
H01J
37/32623 (20130101); C23C 14/564 (20130101); H01L
21/67748 (20130101); H01L 21/67017 (20130101) |
Current International
Class: |
H01L
21/677 (20060101); C23C 14/56 (20060101); H01J
37/32 (20060101); H01L 21/00 (20060101); H01L
21/67 (20060101); C23C 014/34 () |
Field of
Search: |
;204/298.11,298.15,298.25,298.26 ;118/719,723 |
References Cited
[Referenced By]
U.S. Patent Documents
Foreign Patent Documents
Primary Examiner: Nguyen; Nam X.
Attorney, Agent or Firm: Hamrick; Claude A. S.
Claims
What is claimed is:
1. In a processing system including a processing chamber or
subchamber having an opening into which a substrate having a
surface to be coated or otherwise treated may be disposed, lift
means for moving the substrate into and then out of said opening,
and shutter means for temporarily blocking said opening during the
time that a processed substrate is being removed and replaced by an
unprocessed substrate, an improved shutter means, comprising:
a shutter plate having certain physical characteristics
substantially similar to those of a substrate to be processed;
and
shutter plate transport means operative to transport said shutter
plate between a first position alighted with said lift means where
said shutter plate can be engaged by said lift means, lifted from
said transport means and moved into said opening in place of a
substrate, and a second position retracted from said first
position.
2. In a processing system as recited in claim 1 wherein said
substrate is a substantially circular semiconductive wafer and said
shutter plate is a substantially circular plate having a
circumferential size and configuration substantially identical to
that of said wafer.
3. In a processing system as recited in claim 2 wherein said
transport means includes a pivotally mounted plateform for holding
said shutter plate, and drive means for causing said platform to
rotate about a pivot axis in transporting said shutter plate
between said first position and said second position.
4. In a processing system as recited in claims 1, 2 or 3 wherein
said system further includes means for carrying said substrate into
alignment with said means for moving whereby a substrate to be
processed can be loaded onto said means for moving and a processed
substrate can be off-loaded onto said means for carrying for
removal from said chamber.
5. In a processing system as recited in claim 4 wherein said
shutter plate transport means is also operative to position said
shutter plate in alignment with said means for carrying so that
said means for carrying may additionally be used to remove a used
shutter plate from the chamber and to replace it with a different
shutter plate.
6. In a processing system as recited in claim 1 wherein said
transport means includes a pivotally mounted platform for holding
said shutter plate, and drive means for causing said platform to
rotate about a pivot axis in moving said shutter plate between said
first position and said second position.
7. A semiconductor wafer processing system comprising:
means forming a processing chamber having an opening for receiving
a semiconductor wafer to be processed;
lift means for moving a wafer to be processed along a path between
a first position and a second position within said opening; and
shutter means including a shutter plate and a transport means for
transporting said shutter plate between a position in alignment
with said path and a position retracted therefrom, whereby when
said wafer is not disposed within said opening, said shutter plate
may be engaged by said lift means, removed from said transport
means and moved into the position within sad opening normally
occupied by said wafer.
8. A semiconductor wafer processing system as recited in claim 7
wherein said transport means includes a pivotally mounted platform
for holding said shutter plate, and drive means for causing said
platform to rotate about a pivot axis in moving said shutter plate
between said position in alignment and its retracted position.
9. A semiconductor wafer processing system as recited in claim 7 or
8 and further comprising means for carrying a wafer into alignment
with said lift means whereby a wafer to be processed can be
off-loaded from said means for carrying and loaded onto said lift
means for movement into said opening, and a processed wafer can be
off-loaded from said lift means and loaded onto said means for
carrying for removal from said chamber.
10. A semiconductor wafer processing system as recited in claim 9
wherein said transport means is additionally operative to position
said shutter plate in alignment with said means for carrying so
that said means for carrying may be alternatively used to remove a
used shutter plate from the chamber and to replace it with a
different shutter plate.
Description
BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates generally to substrate surface
processing apparatus and more particularly to a removable shutter
mechanism for use in closing the substrate exposure aperture of a
semiconductor processing or other deposition or etching process
chamber.
2. Brief Description of the Prior Art
It is a common practice in the semiconductor processing industry to
plate the surface of a semiconductor wafer with a metal or metal
oxide using a sputtering technique wherein a wafer is disposed in
an evacuated chamber and a metallic material is electrically
removed from an anode and plated onto the wafer surface.
Wafers are normally shuttled in and out of the processing chamber
by a robotic mechanism. The conventional practice is to either
interrupt the plating process each time a wafer is inserted or
removed from the processing chamber, or in the case where the
sputtering operation is continuous, to provide a shuttering
mechanism of some type for covering the opening normally occupied
by the wafer.
In the first case, the primary disadvantage relates to the reduced
throughput of the system, as time must be allowed for ramping up
and ramping down the plating operation.
Apparatus for implementing the second case is illustrated in FIG. 1
of the drawing and includes an evacuable chamber formed by a
housing 10 and closure 12, the lower surface of the closure being
formed by a metallic plate 14 which serves as the system anode.
Also depicted is a source of material to be sputtered onto a wafer
16 shown supported above a heating plate 17 by a lift assembly 18
including four upstanding fingers 19. The system cathode is formed
by a bowl 20 having a central aperture 22 formed therein. Resting
within the bottom of bowl 20 is an annular clamping mechanism 24
having a lip 26 formed about an inner annulus thereof and adapted
to be engaged by the perimeter of wafer 16 as it is raised by lift
assembly 18 into the plating position shown by the dashed lines
16'. The heating plate 17 is movable between the lower position
shown by the solid lines and an upper position immediately beneath
wafer 16' as depicted by the dashed lines 19'.
In order to close the plating aperture 22 during the removal and
replacement of wafer 16, a shutter 32, normally positioned to the
side, is moved into the position shown by the dashed lines 32' so
as to block the path of the plating ions. Since plating material
will build up on the surfaces of both shutter 32, cathode 20 and
clamping ring 24, shutter 32 must be positioned above these
elements a sufficient distance to prevent contact therewith.
Accordingly, in order to be effective the shutter 32 must be much
larger than a wafer. This means that the inner peripheral surface
portion of the clamping mechanism covered by the shutter can not be
reconditioned during the time that the shutter is in position.
Accordingly, the chamber must be periodically opened to allow
access to the clamp.
Furthermore, where a reactive gas is introduced into the chamber to
react with the metal ions and form metal oxides, the oxides that
plate onto the shutter will be somewhat brittle and unless removed
will crack and flake off causing contamination of the chamber.
Accordingly, a particular shutter can only be used for a limited
time after which the chamber must be opened to allow its
replacement. This of course limits the efficiency of the apparatus
and affects the reliability of the system.
Similar apparatus is used to implement etching and other deposition
processes and is subject to the same or similar disadvantages
pointed out above.
SUMMARY OF THE PRESENT INVENTION
Briefly, a preferred embodiment of the present invention includes a
shuttering mechanism disposed within a processing chamber and
adapted to carry a shutter plate in the shape of a wafer or other
substrate to be processed between a retracted position and an
extended position wherein it may be engaged by a lifting assembly
and moved into position closing the normal processing aperture, as
if it were a wafer to be plated or otherwise processed. When a new
substrate is ready to be presented for processing, the lifting
assembly will lower the shutter plate back onto the shutter
transport mechanism and it will be moved to its retracted position
out of the way of the normal substrate handling and processing
operation. Because the shutter plate is geometrically similar to
the substrate to be processed and is handled by the same lift
assembly, the same robotic shuttling mechanism used to move
substrates into and out of the chamber may be used to periodically
remove and replace a used shutter plate with a new plate without
shutting down the system. An important advantage of the present
invention is that the shutter closes, and thus "shadows", exactly
the same processing aperture closed by the substrate during its
processing.
BRIEF DESCRIPTION DRAWING
FIG. 1 is a cross-sectional view schematically illustrating a prior
art processing chamber and shutter mechanism;
FIGS. 2 and 3 are respectively side and top cross-sectional views
showing a processing chamber and shutter mechanism in accordance
with the present invention.
DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS
Referring now to FIG. 2 of the drawing, a preferred embodiment of
the present invention is shown implemented in apparatus adapted to
sputter a metal coating onto a semiconductive wafer. In such
embodiment, a housing 40 is depicted forming an evacuable
processing chamber 42, the upper portion of which forms a
sputtering region wherein metal is sputtered from an anode plate 44
onto the upper surface of a wafer 46". Chamber 42 is openable at
the top and closed by the anode assembly 43 which includes the
anode plate 44 which extends into the circular opening 45 formed in
the top of housing 40. Note that the closure 43 is electrically
isolated from housing 40 by means of an insulative ring 47 and is
pneumatically sealed thereto by means of resilient O-rings 49. The
sputtering region 48 is defined by the anode plate 44, a cathode
forming bowl 50 having a central opening 36 formed in the bottom
thereof, and a wafer clamp 52 the inner periphery 37 of which
defines a plating aperture or opening 38. The anode and cathode are
electrically interconnected in a manner well known in the art.
Disposed within chamber 42 is a wafer heating plate 54 and a lift
assembly 56 including four upstanding wafer-engaging fingers 57.
Heating plate 54 is moved by an actuator 58 between a lower
position, as shown by the solid lines, and an upper position,
indicated by the dashed lines 54' located immediately below the
in-place wafer 46".
As will be further explained below, lifting assembly 56 is moved by
an actuator 59 between a lower position, as shown by the solid
lines, and an upper position indicated by the dashed lines 56'.
Extending from one side of housing 40 is means 41 a communicating
passageway for the shuttle blade 51 of a robotic wafer transport
mechanism 53 which moves wafers into and out of chamber 42 through
a slit 55 as suggested by the dashed lines 51'.
Extending from the right side of housing 40, as depicted, is an
extended housing 60 forming a subchamber 62 which communicates with
chamber 42 by means of a slit 64 and forms a retraction compartment
for a shutter plate 66 and its associated transport arm 68. Arm 68
is connected to the rotatable shaft 70 of a rotary actuator 72 and,
as is more clearly shown in FIG. 3, swings from the retracted
position 68 indicated to an extended position 68' lying above
heating plate 54.
Turning now to FIG. 3, which is a top cross-sectional view taken
generally along the line 3--3 of FIG. 2, it is to be understood
that for convenience and clarity of disclosure certain artistic
license was taken in FIG. 2 to unfold and two-dimensionally
illustrate a cross-section taken along the line 2--2 of FIG. 3. As
depicted, shutter plate 66 rests upon a transport arm base portion
67 and is held in place by upstanding ribs or lips 69, and can be
swung from its retracted position 68 within chamber 62 to its
extended position 68' overlying heating plate 54. Shutter plate 66
is normally a disk configured substantially similar to a wafer to
be processed and is made of a metal, ceramic or other suitable
material.
In operation, referring simultaneously to FIGS. 2 and 3, it will be
understood that a wafer 46 resting atop the transport blade 51 of
robot mechanism 53 can be moved through slit 55 and into the
position 46' where it can be lifted from blade 51 into the plating
position 46" (in opening 38) by the lifting fingers 57. Note in
FIG. 3 that the lift assembly 56 includes a yoke-like structure
including arms 61 that are open at 63 to provide clearance for
blade 51 when it is in the position 51'. As soon as blade 51 is
withdrawn, heating plate 54 can be raised into its wafer heating
position immediately below the bottom surface of wafer 46". Note
that notches 59 are provided in heating plate 54 to provide
clearance for lift fingers 57. The wafer, lift assembly and heating
plate will remain in the raised position for a predetermined period
of time to accomplish the plating operation after Which heating
plate 54 will be lowered, robot shuttle blade 51 will be reinserted
into the position 51', and lift assembly 56 will be caused to lower
wafer 46" onto blade 51' as indicated at 46' (FIG. 2). Assembly 56
will then continue to be lowered until wafer 46' is clear of
fingers 57 and can be withdrawn by blade 51.
As soon as blade 51 has caused wafer 46' to clear the top of
heating plate 54, actuator 72 can be energized to swing arm 68 and
shutter plate 66 into position over heating plate 54 and in
alignment with fingers 57. Actuator 59 will then be energized to
lift assembly 56 into engagement with shutter plate 66, and will
continue to move upwardly raising plate 66 off of arm 68 and into
the plating position previously occupied by wafer 46". This
effectively closes the plating aperture or opening 38 and allows
the system to continue to run. When a new wafer is ready to be
plated, the operative cycle will be reversed, the shutter plate
retracted into chamber 62, and the new wafer moved into position
for plating.
Since the time required to remove wafer 46" and replace it with
shutter plate 66', and vice versa, is very short, little plating
material will, in the interim, pass through the open aperture 38.
This means that the temperature and pressure of the chamber can be
held substantially constant with the result that the plating
quality from wafer to wafer will be more uniform.
Another advantage of the present invention is that since lift
assembly 56 lifts both wafer and shutter plate in the same manner
and both are of substantial size and shape, the exchange cycle can
be periodically altered to remove and replace a shutter plate "on
the fly". This is to say that when a shutter plate change is
desired, instead of lowering the shutter plate onto the transport
arm 68, the arm can be swung to the side empty and shuttle blade 51
can be inserted into position over heating plate 54. The shutter
plate can then be lowered onto blade 51 and transported thereby to
a discharge bin or cleaning chamber. A new shutter plate can then
be returned on blade 51 to the chamber 42 where it can be lifted
from blade 51 by assembly 56 and then lowered onto transport arm 68
to assume its operational role. This of course means that
heretofore unattainably high levels of system reliability and
efficiency and low levels of contamination can be achieved and
maintained.
Although a swing arm configuration has been disclosed above as the
preferred means of moving a shutter plate into and out of the lift
system, it will be appreciated that in the alternative a
reciprocatable blade type, or any other suitable type of shutter
transport means could be utilized to present the shutter plate to
the lift assembly or to itself lift the shutter plate into the
plating aperture. Furthermore, it will be appreciated that the
novel combination of functional elements disclosed above is not
limited to sputtering applications and in fact will have
application in similar apparatus used to implement many other
substrate deposition and/or etching processes.
Accordingly, since numerous alternate applications, alterations and
modifications thereof will no doubt become apparent to those
skilled in the art after having read this disclosure, it is
intended that the appended claims be interpreted broadly to cover
all such applications, alterations and modifications as fall within
the true spirit and scope of the invention.
* * * * *